Process and apparatus for controlling heat and combustion in pottype hydrocarbon fuel burners



March 30, 1954 H. c. LITTLE 2,573,605

PROCESS AND APPARATUS FOR CONTROLLING HEAT AND COMBUSTION IN POT-TYPEHYDROCARBON FUEL BURNERS Filed April 24, 1948 uoooun oooooonooocoooooqoO OOOOOOOO/OO INVENTOR. HAP/er 6 L/rr4 Patented Mar. 30, 1954 UNITEDSTATES PATENT OFFICE PROCESS AND APPARATUS FOR CONTROL- LING HEAT ANDCOMBUSTION IN POT- TYPE HYDROCARBON FUEL BURNERS 8 Claims.

This invention relates to the regulation of burners of the type in whichthe hydrocarbons are generally vaporized and mixed with air in a fuelgenerating chamber and then burned at a throat or outlet leading fromthe chamber where secondary air is supplied, the heat of the burningfuel at the throat serving to radiate heat to the hydrocarbons so as tovaporize the same for admixture with primary air supplied to thechamber.

Distillates of the types presently most generally available are productsof modern catalytic cracking processes and are those which remain afterthe major portions of the more volatile fractions of the crude oil havebeen extracted. As a result of this, the so-called burner oils nowrequire greatly increased temperatures to transform them to the vaporouscondition necessary to insure complete and efficient combustion of thefuel. The conventional burner is generally incapable of developing, inthe burner flame, a temperature suificiently high to thoroughlyvolatilize the catalytic-process distillates with the result that theburner operates not only at reduced eificiency so as to create anexcessive amount of smoke and soot deposit, but promotes surging orperiodic burning back into the vaporizing area of the fuel generatingchamber.

An object of the invention is to provide an improved process andapparatus for effecting efficient combustion of, and for deriving amaximum amount of heat from characteristically refractory burner fuelssuch as the high boiling-point distillates obtained as products in thecatalytic refining of crude oil.

Another object of the invention is to provide, in connection with aburner having a throat at which may burn a principal flame resultingfrom an ignited admixture of air and hydrocarbon fuel vapor generated ina vaporizing chamber containing a body of liquid fuel exposed to thermalradiation from the principal flame, a means independent of said thermalradiation which will increase the temperature within the vaporizingchamber greatly in excess of that capable of being produced by theprincipal flame alone so as to create a highly combustible mixture ofvapor and air in the chamber and, at the same time, which will inhibitpremature ignition of the highly combustible mass of vaporized fuel andair prior to the latter coming within normal ignition range of theprincipal flame.

A further object of the invention is to provide, in a burner of thecharacter described, apparatus which will institute a regenerativeaction in the burner vaporizing chamber whereby a portion of the fuelvapor created in the chamber by thermal radiation from the principalflame is utilized for creating supplemental direct and radiated heat soas to greatly increase vaporization in the chamber thereby enriching thevaporous fuel supply of the principal flame and corre-- spondinglyincreasing the flame heat so as to augment the normal vaporizationcaused by the principal flame and to increase the density of fuel vaporavailable and utilized for creating the aforesaid direct and radiatedheat.

A. further object of the invention is to provide an improved burner ofthe class described which is characterized by the production of a,quieter fire, which indicated more efficient combustion by the depositof less soot than ordinarily accumulates in burners of similar types,and which is less susceptible to the condition known as surging whereinthe flame burning exteriorly of the generator or fuel vaporizing chamberrecedes to burn persistently within the chamber with an accompanyingsevere loss in combustion efficiency.

Still another object of the invention is to provide heat controlapparatus which may be readily attached to and incorporated in mosttypes of conventional hydrocarbon fuel burners of the character referredto without necessitating extensive structural changes in the latter.

The invention possesses other objects and features of advantage, some ofwhich, with the foregoing, will be set forth in the followingdescription of the preferred form of the invention which is illustratedin the drawing accompanying and forming part of the specification. It isto be understood, however, that variations in the showing made by thesaid drawings and description may be adopted within the scope of theinvention as set forth in the claims.

Referring to the drawings:

Figure 1 is a top plan View of an oil burner equipped with the improvedheat control apparatus of my invention. Portions of the view are brokenaway so as to more clearly disclose the internal structure.

Figure 2 is a vertical sectional View taken in the plane indicated bythe line 2-2 of Figure 1.

Figure 3 is a top plan view of the burner showing a modified form ofheat control apparatus embodied therein.

Figure 4 is a side elevational view of the structure of Figure 3 with aportion of the burner broken away so as to more clearly show the heatcontrol apparatus, the latter being shown in vertical section. r

Figure is a vertical sectional view of a cylindrical type of burnerhousing showing a ring type air heating device of my invention includedtherein.

In the drawings I have shown a burner of the fuel evaporation class suchas disclosed in my prior Patent No. 2,109,946 and comprising asillustrated in Figures 1 and 2, housin 6 defining a generating orvaporizing chamber 7 at the bottom portion of which a pool 8 of liquidhydrocarbon fuel is arranged to be created, the fuel being admitted froma suitable source of supply, and at a pre-regulated rate, through aninlet 9 provided in the housing. The upper portion of the housing isprovided with an opening or burner throat I I; and a plurality ofapertures l2, pierced through the housing side walls, serve to admitprimary combustion-supporting air to the chamber 1. In some burners ofthis type, ignition is instituted by introducing a flaming wad of paperor the like into the chamber 1 through an inspection door such as shownat l3 so as to raise the oil in the pool 8 to ignition temperaturewhereupon the rising vapors will combine with air admitted through theapertures l2 and, becoming ignited, will issue as a flame from theburner throat II. Other burners are equipped with electrically energizedglow devices or oil-fired pilot flames for initiating vaporization andcombustion of the fuel. When the usual fuels having the relatively highproportion of readily vaporizable combustible fractions such aspreviously readily obtainable, was utilized for the operation of thetypical burner thus described, the action of the burner flameestablished at the throat was to effect vaporization of the oil bythermal radiation from such flame and by heat conducted through thehousing to the pool 8.

To permit, in such typical or other burners, use of catalyticdistillates as the oil burner fuel instead of the fuel with the highpercentage of the combustible fractions aforesaid, I provide forutilization with the burner, a novel means and process which involves inthe preferred embodiments of the invention, the projection directly intothe vaporization chamber of numerous tongues or jets of flame consistingof volatile components of the fuel vapor in the vaporizing chamber andhighly heated air drawn from a restricted air chamber. This burningcreates a controlled high temperature in the vaporizing chamber so as togreatly increase the rate of vaporization but without increasing thecombustion of the mixture in the vaporizing zone of the chamber. Theaforesaid burning action may be provided for by a wide variety ofmechanical arrangements, several of which are here explained.

In each of the arrangements here illustrated, an air heating chamber isprovided in association with the vaporizing chamber and communicatestherewith through a plurality of small perforations contained in a wallor other element separating the chambers from each other.

As shown in Figures 1 and 2, as an example, the top wall member I4 ofthe housing 6 is provided with a comparatively large number of smallapertures l6 each of which is about .086 inch in diameter, which formpassages to the vaporization chamber I from an air heating chamber I!disposed above the housing 6 and formed by a recessed cap member 18, thelatter overlying the apertures Hi and sealed to the top wall member N.in, any suitable manner such as by screws IS. The cap member I8' isimperforate except for an aperture 2| (or a plurality if desired) in thetop thereof which may be partially or fully opened by a shutter valve 22superposed thereover and preferably forming part of an arm 23 which ismounted by a screw 24 or the like to swing over the cap member. Theshutter valve forms the common control means for regulating the supplyof air to all of the apertures I6. A downturned end portion 2'5 of thearm is adapted, preferably, to frictionally engage a portion of the capmember or burner housing so that an adjustably fixed regulation of theuncovered area of the aperture 2| may be secured. Instead of bein on thetop wall 14, the chamber I! may, as shown in Figures 3 to 5 of thedrawings, be provided in a separate housing 21 positioned at anysuitable location directly within the vaporization chamber 1. In suchcase, as in the embodiment shown in Figures 3 and 4, the housing 21 maybe supported by means including a tubular arm 28 extending from thehousing and passing through an aperture provided therefore in a wallmember of the main burner housing 6. The arm 28 has a longitudinalpassage 28 therein which carries air from exteriorly of the burner intothe air heating chamber I? and a shutter valve 3| is provided andadopted for operation similar to the valve 22.

For the purpose of explanation reference will be made to the embodimentof the invention shown in Figures 1 and 2. When the burner has beenignited for a short time, the jet flames at the apertures l6, will, asthe result of the heat rising therefrom and conducted through the burnertop wall [4, highly heat the air contained in the chamber H, which airwhen passing through the apertures [6 will readily mix with fuel vaporin the uppermost portion of the vaporization chamber and thus effectcontinued propagation of the jet flames The jet flames are very blue incolor and are comparatively short, extending approximately no more thanabout A; of an inch downwardly into the vaporization chamber. In theoperation of the burner of my invention, and as a very important featurethereof, the cross-sectional area of the aperture 2! to the chamber H isless than the combined cross-sectional area of the apertures It, thusrestricting the flow and reducing the velocity of the air from chamber Hto the vaporizing chamber. In other words the flow from the apertures [Binto the vaporizing chamber will be restricted and at a much lowervelocity than the air entering the vaporizing chamber through theapertures l2. The very low velocity of the air passing from the chamberI! through the jet apertures [6 accounts for the shortness of the jetflames and the restricted volume of the air is sufficient only tosupport the desired combustion for the production of the aforesaid veryblue flames. As will be understood, when the burner is operating andcombustion is taking place at the throat II, a considerable draft isinduced in the vaporization chamber so that the pressure therein will beless than that of the pressure in chamber l1, and consequently therewill be a flow of air from chamber i! into the vaporizing chamber.

Operation of the burner in this manner, even for a very short time,increases the temperature of the vaporizing chamber and of the flameburning at the throat II by several hundred degrees Fahrenheit over thatnormally procurable in conventional types of burners. This intense heatgenerated by the flames burning at the apertures IS, in cooperation withthe heat generated from the main flame, burning at the orifice, H, isradiated through the mass of comparatively heavy'fuel vapor to finallypermeate the portions of the pool of liquid fuel. In this manner theheavier air-borne components of the fuel mixture in the generatingchamber will be broken down to more nearly approach a gaseous phase, andthe body of the liquid fuel will become so thoroughly and highly heatedthat it is very rapidly and completely vaporized. It will thus beevident that with the higher temperatures obtainable in the burner of myinvention, the complete volatilization of the average catalytic-processdistillates may be readily effected.

As the result of the thermal radiation from both the main burner flameand th numerous jet flames, a temperature will be attained in thevaporizing chamber which is considerably above the flash points of thefluid contents therein both in its liquid and vaporous phases. It willthus be evident that in a conventional burner and under ordinaryconditions, such a temperature would result in the ignition andcombustion of said contents in the chamber and produce the objectionablecondition known in the art as surging. It is a peculiar phenomenon ofthe present invention that notwithstanding the highly heated andvaporized condition of the fuel, the combustion thereof in thevaporizing zone of the chamber will be inhibited until it reaches thezone of the burner throat.

Exactly what occurs in the vaporizing or genorator chamber is notentirely clear for the rea son that several actions may take place whichprevent said combustion with resultant surging. It may well be that thecontinuous generation of carbon dioxide and other products of combustionfrom the small blue flames steadily burning from the heat controlchamber, thins out and modifies the oil and vapor mixture to the extentthat combustion in the vaporizing zone of the burner is prevented. It isalso possible that the heat control arrangement of my invention causes achemical reaction to take place within the burner chamber which producesa burning mixture quite different from the mixture ordinarily formed inthe conventional burner, and that this mixture, so formed under highertemperatures and with the added products of combustion from themultiplicity of small blue flames contains a high proportion ofalcoholic vapors.

I have found that burners, when equipped with i the heat controlarrangement of my invention have a much smoother and quieter fire. Also,as previously explained, not only does the aforesaid arrangementeliminate the periodic surging, but no carbon will accumulate within thegenerator chamber even when burning the heavy catalytic oils.

I have also found in testing the burner of my invention that when bettergrades of fuel are used, most satisfactory fuel vaporization and burnerperformance will be obtained when the jet flames are located at thelower surface of the chamber top wall l4. However when lower grade fuelsare used, which have smaller amounts of the low-boiling point fractions,it has been found better to bring the jet flames into closer prox imitywith the surface of the oil pool. This may be accomplished, bypositioning the auxiliary housing 21 in the vaporization chamber at sucha location that the jet flames are sufliciently close to the oil pool toinsure thorough heating thereof and to effect substantially completereduction of the liquid thereof to the vaporous phase. Thus in Figure 5is shown a burner of common form having a cylindrical housing 32provided e burner orifice 3d.

6 in its top wall 33 with a burner orifice 34 disposed substantiallycentrally above the fuel vapor generation chamber at, an air heaterhousing 3? being provided with the chamber 36, which is hollow to definean air chamber 38 connected by means of one of more tubes 39 with theburner housing 32. The tubes 39, besides serving as supports for the airheater housing, provide ducts l! through which outside air may enter thechamber 38, the exterior ends of the ducts being capable of fractionalor complete exposure by means of shutter valves 42 cooperating therewithand mounted for pivotal movement by means of screws 43 or the like onthe burner housing 32. In the drawing I have shown the air heaterhousing as a disk-shaped body which occupies substantially the entirecross-sectional area of the chamber 35 with the exception of a centralportion thereof defined by an opening 4t extending vertically throughthe air heater housing 3? and positioned substantially directly belowthe burner orifice 3d. The underside of the housing BI is provided witha large number of small holes 35 entering the chamber 38 and at whichthe jet flames described above may burn to heat the vapor content of thechamber and to project heat downwardly toward the surface of the oilpool. If desired holes 46 may also be provided at the chamber 38. Thusthe combustion gases and the highly heated fuel vapor may pass upwardlythrough the opening 44 and thence directly through the burner orifice34. It will of course be obvious that instead of the ringshaped diskhousing shown in Figure I may choose to employ a solid disk type ofhousing which may be positioned and sized to underlie the burner orificewith the gas and vapor passage defined by a peripheral gap between themargin of the disk and the adjacent wall surface of the burner housing32. Thus the gases and vapor generated will be caused to rise in theperipheral zone of the generator chamber 36 and will be caused, by thehousing top wall 33, to move convergently toward and through the Ineither case, a desired turbulence in the fluid contents of the generatorchamber is effected which, together with the high air temperature andcombustion inhibiting action produced by the jet flames will producegreatly improved combustion in the main flame burning at the burnerorifice and greatly increase the capacity of the burner.

Iclaim:

1. In a natural draft burner for hydrocarbon fuel having a housing witha horizontally elongated chamber into which may be admitted,respectively, fuel to be vaporized and primary air to be combined withvaporized fuel to form a combustible mixture, and said housing beingfurther provided with a burner throat overlying the chamber adjacent oneend thereof and through which the fuel mixture may flow and in whichsaid fuel mixture may burn as a flame issuing from the housing, toradiate heat into the chamber to contribute toward vaporization of fueltherein and to induce a draft of air into the chamber to form with thefuel vapor a combustion propagating component of said fuel mixture,pie-ignition means overlying the chamber adjacent the other end thereofand including means to introduce a separate flow of air into the chamberover substantially the remaining portion of the chamber to combine withvaporized fuel therein and to form a separate fuel mixture ignitable toburn within and to separately radiate heat into the chamber to furthercontribute to said fuel vaporization, and means for controllingadmission of said separate flow of air, said separate air flow meansbeing in direct vertical flow communication with the fuel in saidremaining portion of the chamber whereby the burning thereat willradiate heat directly toward said fuel.

2. In a natural draft burner for hydrocarbon fuel having a housing witha horizontally elongated chamber into which may be admitted,respectively, fuel to be vaporized and air to be combined with vaporizedfuel to form a combustible mixture, and said housing being furtherprovided with a burner throat overlying one portion of said chamberthrough which the fuel mixture may flow and in which said fuel mixturemay burn as a flame issuing from the housing, to radiate heat into thechamber to contribute toward vaporization of fuel therein and to inducea draft of air into the chamber to form with the fuel vapor a combustionpropagating component of said fuel mixture, a housing member associatedwith said burner housing and defining an air chamber elongated in thedirection of elongation of the burner chamber and contiguously relatedto and overlying substantially the entire remaining portion of saidburner chamber, means to introduce a controlled flow of air into saidair chamber, and means including a plurality of jet openings positionedover the full length of the air chamber to conduct air from said airchamber into said burner chamber to be mixed with fuel vapor in thelatter and ignitable to burn as flames from said jet openings inproximity to said air chamber and exposed within said burner chamber,said flames being separate from said throat flame and disposed over thefuel in said remaining chamber portion whereby the heat from said flameswill be radiated directly toward the fuel located under said airchamber.

3. An oil burner comprising a housing providing a horizontally elongatedoil-vaporizing and air-mixing chamber, means providing a pool of oilalong the bottom of the chamber, said housing having a burner throat atthe top thereof overlying one portion of the exposed surface of saidpool, said housing also having openings in its sides for admittingprimary air to the chamber over substantially the entire surface of saidpool, means supplying secondary air to said throat, a casing providingan air chamber along the upper portion of said first chamber and havinga plurality of jet openings in the bottom thereof overlying the otherportion of the surface of said pool, said jet openings being disposed ata level lower than said secondary air means and arranged to propagateflames therefrom to radiate heat directly toward said other portion ofthe pool surface, and means for controlling the supply of air to saidcasing.

4. An oil burner having a housing provided with an oil-vaporizing andair-mixing chamber, means providing a pool of oil along the bottom ofsaid chamber, said housing having a burner throat at an upper portionthereof overlying one portion of the exposed surface of said pool, saidhousing also having openings in the side thereof for admitting primaryair to the chamber over substantially the entire surface of the pool,means supplying secondary air to said burner throat, a casing providingan air chamber substantially at the top of said first chamber and havinga plurality of jet openings providing communication between saidchambers and positioned directly over the other portion of the surfaceof the pool, said jet openings being laterally offset and disposed belowthe level of said secondary air means, air supplying means independentof said primary air openings and said secondary air supplying means foradmitting air to said casing, the effective area of the air supplyingmeans for said casing being less than the total cross-sectional area ofsaid jet openings.

5. An oil burner comprising a housing having side, top and bottom wallsdefining a horizontally elongated oil vaporizing chamber, said top wallhaving a burner throat therein adjacent one end of said chamber, saidside walls being perforated to admit primary air to the chambersubstantially throughout the length thereof and having a substantiallyimperforate portion adjacent the top thereof near the other end of thechamber, secondary air supply means at said throat to provide with saidprimary air and oil vapor a combustible mixture to burn at said throatand thereby radiate heat in the chamber to vaporize the oil therein andinduce a draft from said perforations to said throat, a casing providingan air chamber adjacent the top and said last mentioned end of thevaporizing chamber and having a bottom wall with air discharge openingsin the zone of said imperforate side wall portion, and air supply meansto said casing.

6. An oil burner comprising a housing having top and bottom walls andelongated opposing side walls and front and rear side walls defining anelongated oil-vaporizing and air mixing chamber, means adjacent saidrear side Wall and cooperating with the top wall of the housing to forma burner throat for the chamber, said elongated and rear side wallshaving openings therein for admission of primary air to the chamber,said side walls having a substantially imperforate portion adjacent thetop wall and front side wall, means providing a pool of oilsubstantially over the entire length of the bottom wall, a casingpositioned within the chamber opposite and between said imperforateportions and entirely removed from under the throat, said casing havingtop, side and bottom walls defining an air chamber, the top wall of saidcasing being substantially imperforate and said bottom wall of thecasing being formed with jet openings, and means securing said casing tothe front Wall of the housing and providing a passage for air to saidcasing chamber from exterior of the housing.

'7. The process of vaporizing oil and mixing the same with air in ahorizontally elongated chamber for discharging and burning in a throatat the top and adjacent one end of the chamber, which comprises theintroduction of a thin film of oil across the entire bottom surface ofsaid chamber, admitting primary air to said chamber along substantiallythe entire length thereof and closely adjacent to the surface of theoil, supplying secondary air for admixture with the air and oil mixturedischarging at the throat, the amount of said primary air and oil in thecham-- her being such that a combustible mixture will be provided withsaid secondary air and burned at said throat, supplying jets of airindependent of said primary and secondary air to the mixture in thechamber along the upper portion thereof laterally remote from saidthroat, selectively controlling the amount of said air jets, said amountbeing sufficient to provide a zone of limited combustion in proximity tothe supply of air for said jets for preheating said supply prior to theintroduction of said jets in the chamber and. for increasing thevaporization of the oil in the chamber.

8. The process of vaporizing oil and mixing the same with air in ahorizontally elongated chamber for discharging and burning in a throatat the top and adjacent one end of the chamber, which comprises theintroduction of a thin film of oil across the entire bottom surface ofsaid chamber, admitting primary air to said chamber along substantiallythe entire length thereof and closely adjacent to the surface of theoil, without effecting burning of said primary air in said chamberadjacent the admission thereof, supplying secondary air for admixturewith the air and oil mixture discharging at the throat, the amount ofsaid primary air and oil in the chamber being such that a combustiblemixture will be provided with said secondary air and burned at saidthroat, supplying jets of air independent of said primary and secondaryair to the mixture in the chamber along the upper portion thereoflaterally remote from said throat and at an entering velocitysubstantially less than the primary air velocity, selectivelycontrolling the quantity of said air jets, said amount being sufficientto provide short streaks of blue flame in proximity to the supply of airfor said jets for pre-heating said supply prior to the introduc- 19 tionof said jets in the chamber and for increasing the vaporization of theoil in the chamber subjacent said jets.

HARRY C. LITTLE.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 2,109,946 Little Mar. 1, 1938 2,162,844 Jenson June 20, 19392,214,670 Gilmore et al Sept. 10, 1940 2,316,226 Dc'nley Apr. 13, 19432,337,673 IVIzCurtain Dec. 28, 1943 2,339,614 Breese Jan. 18, 19442,346,781 Perry Apr. 18, 1944 2,353,439 Breese et a1 July 11, 19442,357,587 Hammell Sept. 5, 1944 2,363,192 Miller Nov. 21, 1944 2,369,833Livar Feb. 20, 1945 2,381,744 Hayter Aug. 7, 1945 2,393,176 Livar et a1.Jan. 15, 1946 2,393,233 Breese Jan. 22, 1946 2,396,820 Breese Mar. 19,1946 2,401,086 Little May. 28, 1946 FOREIGN PATENTS Number Country Date392,371 France Sept. 23, 1908

